Modified cellulose ethers

ABSTRACT

The invention relates to a cellulose ether that is hydrophobically modified with an alkyl or alkenylketene dimer of general formula (I), in which R 1  and R 2  are alkyl or alkenyl chain,                    
     such as one having 5 to 22, preferably 13 to 20, most preferably 14 to 18 carbons. The product can be used in water-based products to control the rheological properties, for example. Objects of use include, for example, detergents, paper coating mixtures, paints, dispersing agents, and oil drilling muds.

BACKGROUND OF THE INVENTION

The invention relates to hydrophobically modified cellulose ethers andto the use thereof.

Cellulose ethers, such as carboxymethyl cellulose, are employed in awide variety of applications to treat the rheological properties ofaqueous solutions in particular. Objects of use include, for example,foods, medicines, cosmetic preparations, detergents, agriculturalchemicals, textiles, printing inks, paper coating agents, constructionmaterials, adhesives, paints, ceramic materials, and additives ofpolymerisation.

Cellulose ethers can be modified by attaching different substituents tohydroxyl groups in cellulose. In this way, the solubility or thehydrophobicity of cellulose ether in particular can be affected.

There is a lot of literature concerning the hydrophobic modification ofpolysaccharides.

U.S. Pat. No. 4,228,277 describes the modification of non-ioniccellulose ethers, such as methyl cellulose, methyl hydroxypropylcellulose, hydroxypropyl cellulose, and particularly hydroxyethylcellulose, by using epoxyalkanes having a length of the alkyl group of10 to 24 carbons. According to the patent, one advantage of themodification is that even small amounts of hydrophobically modifiedcellulose ether make the viscosity of an aqueous solution increase sothat the dosage of the cellulose ether can be decreased. The celluloseether thus modified can be used in paints. The modification is carriedout by using a cellulose ether as a starting material, and the reactiontimes are long, 2 to 5 hours. However, it is uncomfortable to use epoxycompounds because they are detrimental to health.

In FI Patent No. 95138, carboxymethyl hydroxyethyl cellulose is modifiedby an alkyl group having 8 to 25 carbons in an amount of 0.1 to 4% byweight. This product is also applied to paints. The alkyl reagent can behalide, halohydride, or epoxide, all of which are hazardous toenvironment and health. Hydroxyethylation, hydrophobic modification, andcarboxymethylation are carried out in sequence, therefore the reactiontime is long, more than 4 hours.

U.S. Pat. No. 5,302,196 describes cellulose ethers which are modified bya fluorine-containing alkyl group having 3 to 24 carbon atoms, thefluorine content being 0.05 to 5% by weight. The cellulose ether isespecially hydroxyethyl cellulose, hydroxyethyl carboxymethyl celluloseor methyl hydroxyethyl cellulose. The fluorine-containing alkyl reagentis preferably epoxide, bromide or perfluoroolefin. This product is alsodeveloped for paints. The reaction is long, the modification requires areaction time of 6 hours.

In EP Patent Application No. 384167, cellulose ether, especiallyhydroxyethyl cellulose, is modified with an aromatic alkyl group havingat least 10 carbons, the content being 0.001 to 0.1 moles per one moleof a glucose repeat unit of the cellulose ether. The alkyl reagent canbe, for example, halide, oxirane, acid, (thio)isocyanate or halohydrin.The product can be used in latex paints. This manufacturing process alsohas a long reaction time, 6 or up to 12 hours.

GENERAL DESCRIPTION OF THE INVENTION

According to the independent claim 1, hydrophobically modified celluloseethers have been invented. The dependent claims disclose some preferredembodiments of the invention.

This invention introduces a new type of hydrophobically modifiedcellulose ether in which the modifying agent is alkylketene dimer. Thecellulose ether is preferably carboxymethyl cellulose or sodiumcarboxymethyl cellulose (CMC, NaCMC).

Cellulose ether modified with alkylketene dimer is easy to manufacture.The process is safe, simple, and quick. The modification can alsoimprove the dispersability of cellulose ether in water.

The product is suitable to be used in any water-based application. Thehydrophobic group renders the substance properties that are advantageousto, for example, detergents, paper coating mixtures, paints, dispersingagents, and oil drilling muds.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, alkylketene dimer (AKD) is used to modifythe cellulose ether. The general formula of AKD is

in which R₁ and R₂ are alklyl or alkenyl chains having 5 to 22,preferably 13 to 20 carbons. R₁ or R₂ can also be substituted or theycan contain heteroatoms in a chain. R₁ or R₂ can in particular have astraight chain and contain 14 to 18 carbons.

AKD reacts with the hydroxyl group of cellulose or cellulose ether,forming the following formula:

Elevated temperatures, such as 30-120° C., preferably 50-90° C., andmost preferably 60-85° C., enhance the reaction, so that at the elevatedtemperatures AKD is melted first. High temperature and alkaline pHimprove the reactivity of AKD with cellulose ether. AKD can react withthe substituent, for example carboxymethyl group in cellulose ether. AKDcan also react with other compounds which contain an OH group. Theseinclude water, alcohol, and sodium glycolate which are generated in thepreparation of CMC. The thus generated compounds also have an effect onthe hydrophobicity of the product.

The reacted AKD concentration in the cellulose ether can be analysed byusing gas chromatography. The unreacted AKD or AKD reacted with other OHcontaining compounds are extracted with a suitable solvent. The sampleis hydrolysed causing the cleavage of alkyl ketene group. The reactedAKD is extracted with a suitable solvent and analysed with gaschromatograph.

The AKD can be in a solid state or dispersed in water or other solvents.

The content of AKD in the cellulose ether can be 0.001-10% by weight.The content is preferably 0.01-2% by weight.

The molecular weight (Mw) of the cellulose ether can be 10 000-1 000000, preferably 20 000-700 000. The cellulose ether can be, for example,alkyl, hydroxyalkyl or carboxyalkyl substituted or a mixed ether ofthese.

According to the invention, cellulose ether that is modified by AKD canbe used in any water-based application. It can be used, for example, inpaper or board coating mixtures, in the wet end in paper or boardmanufacturing, paints, construction materials, adhesives, oil drillingmud, detergents, cosmetic products, and as a dispersion agent.

The cellulose ether is preferably carboxymethyl cellulose (CMC). Itsdegree of substitution (DS, i.e., the average number of substitutedhydroxyl groups in a glucose ring) can be for example, 0.2-2.0,preferably 0.4-1.5, most preferably 0.4-1.2. Its molecular weight ispreferably 40 000-500 000. It can be applied to all the above-mentionedobjects.

The cellulose ether can also be, e.g., hydroxyethyl cellulose (HEC). Itsmolecular weight can be, for example, 90 000-1 300 000 and the molarsubstitution (MS) 1.5-4. HEC can be used in coating, constructionmaterials, and cosmetic preparations in particular.

The cellulose ether can also be, e.g., hydroxypropyl cellulose (HPC).Its molecular weight can be, for example, 80 000-1 150 000 and the molarsubstitution (MS) 1.5-4. HPC can be used in foods, medical preparations,and coating in particular.

There is a lot of literature about the manufacture of cellulose ethers.Generally, cellulose ethers are prepared by mixing wood-based or cottonwool-based raw material with a reaction medium, such as alcohol oracetone, and by mercerising it with an alkalic substance, such as sodiumhydroxide, to activate the cellulose. An etherifying chemical is addedand it is allowed to react. The complete product is neutralised. Theviscosity can be reduced if needed. By-products, such as salts generatedin the reaction, are washed out with alcohol, for example, when purifiedcellulose ether is manufactured, but they can also be left in theproduct or only remove partly (technical or crude cellulose ether). Thesolvent used is separated and the product is dried. The particle sizeand the bulk density can be adjusted by grinding the product into powderor by granulating it. The product can also be screened.

Cellulose ether can be modified with AKD by various methods. AKD can beadded to the cellulose ether at any stage of the production, forexample, in mercerisation, etherification, or drying. AKD can be addedin a solid form or as a dispersion. High temperature and alkaline pHimprove the reactivity of AKD with cellulose ether.

AKD can also be added to the cellulose ether as such. The celluloseether can be coated, for example, with solid AKD or an AKD dispersion.In that case, a suitable amount of AKD is sprayed onto the surface ofthe cellulose ether or mixed with it. The product is treated with hightemperature to initiate the reaction.

The manufacture of the hydrophobically modified cellulose etheraccording to the invention is simple and quick. Neither complex solventsnor long reaction times are needed. In addition, AKD is a safe chemical.It is neither combustible nor explosive; therefore, it neither causes adanger in a process nor is it dangerous to the environment. AKD is nothazardous or irritating and it does not cause allergies; therefore, itdoes not present any danger to the process personnel or the end-user.

The hydrophobically modified cellulose ether is especially useful indetergent compositions. The cellulose ether is preferably carboxymethylcellulose (CMC). Its degree of substitution is most preferably 0.4-0.6.The compositions generally comprise about 0.1-5% by weight of cellulosicbased fabric treatment components, preferably 0.5-4%, most preferably0.75-3%. The detergent composition can be in liquid, paste or granularform. The compositions comprise about 1-80% by weight, preferably 5-50%of detersive surfactants which can be of the anionic, nonionic,zwitterionic, ampholytic or cationic type. The compositions may alsocomprise about 0.1-80% by weight of a detergent builder, preferably1-10% in liquid form and 1-50% in granular form. Detergent builders cancomprise, for example, phosphate salts as well as various organic andinorganic nonphosphorus builders. In addition to the surfactants,builders and cellulosic based materials, the detergent compositions canalso include for example enzymes and enzyme stabilizing agents, sudsboosters or suds suppressers, anti-tarnish and anticorrosion agents,soil suspending agents, soil release agents, germicides, pH adjustingagents, non-builder alkalinity sources, chelating agents, organic andinorganic fillers, solvents, hydrotropes, optical brighteners, dyes andperfumes.

Granular detergent compositions are generally made by combining baseingredients as a slurry and spray drying the resulting slurry to a lowlevel of residual moisture. The remaining ingredients can be admixed asdry or in case of liquid form, sprayed onto the resulting granules.Liquid detergent compositions can be prepared by admixing theingredients in any desired order.

Laundering of fabrics and textiles in washing solutions containinghydrophobically modified cellulose ether, followed by rinsing anddrying, imparts fabric appearance benefits to the fabric and textilearticles so treated. Such benefits can include improved overallappearance, pill/fuzz reduction, antifading, improved abrasionresistance, and/or enhanced softness.

EXAMPLES

All examples employed alkylketene dimer, the length of the alkyl groupbeing 16 to 18 carbons (Raisio Chemicals).

Example 1

100 g of CMC (Metsa Speciality Chemicals) having an average molecularweight of 180 000 and a degree of substitution of 0.65 was put into asteel container. 1 g of alkylketene dimer dispersion having an AKDcontent of 10% by weight, diluted with 50 g of water, was sprayed onCMC, agitating the powder at the same time. The product was dried at 80°C. to a moisture content of less than 8%. The AKD content of the endproduct was 0.1% by weight.

Examples 2-6

By using the procedure described above, the following hydrophobicallymodified CMC samples (examples 2-6) were prepared:

TABLE 1 Molecular weight Degree of substi- AKD content in Example of CMCtution of CMC CMC, % by weight 2 60 000 0.72 0.05 3 300 000 0.80 0.05 4220 000 0.87 0.1 5 305 000 1.15 1.0 6 80 000 0.75 0.01 Sample 5contained 0.02% by weight of AKD which had reacted with CMC.

Example 7

100 g of CMC having an average molecular weight of 40 000 and a degreeof substitution of 0.79 was put into a steel cylinder. 5 g of solidalkylketene dimer was added. The powder was agitated in an oven at 60°C. for 120 minutes and at 105° C. for 15 min. The AKD content of the endproduct was 5.0% by weight.

Example 8

Hydrophobically modified CMC having an average molecular weight of 400000 and a degree of substitution of 0.86, and an AKD content of 10.0% byweight, was prepared according to the procedure described in example 7.

Example 9

47 g of wood pulp (Metsä-Botnia), 175 g of ethanol, and 20 g of waterwere mixed together in a closed glass flask which was provided with amixer and a nitrogen atmosphere as an option. The flask was placed in awater bath. 18 g of sodium hydroxide, diluted with 18 g of water, wasadded and the cellulose was mercerised for 30 minutes at 20° C. 22 g ofmonochloracetic acid, diluted with 6 g of water, and 1.25 g ofalkylketene dimer dispersion having an AKD content of 20% by weight wereadded and the temperature was raised in 55 minutes to 65° C. Thecellulose was etherified for 60 minutes at 65° C. Ethanol was recoveredand the product was dried at 80° C. to a moisture content of less than8%. The AKD content of the end product was 0.3% by weight, the averagemolecular weight 150 000, and the DS of the carboxymethyl group 0.57.The sample contained 0.02% by weight of AKD reacted with cellulose.

Examples 10-15

Samples 10-15 were prepared according to the procedure described inexample 9. In example 10 and 15 the product was neutralised afteretherification with hydrochloric acid. In example 10 AKD was added afterneutralisation and allowed to react 5 minutes at 70° C.

TABLE 2 Molecular weight Degree of substi- AKD content in CMC, Exampleof CMC tution of CMC % by weight 10 180 000 0.46 0.6 11 120 000 0.48 0.612 140 000 0.52 0.06 13 150 000 0.55 1.1 14 140 000 0.56 2.7 15 270 0000.52 0.06 Sample 12 contained <0.01% by weight of AKD which had reactedwith CMC.

Example 16

100 g of wood pulp (Metsä-Botnia), 1270 g of isopropanol, and 162 g ofwater were mixed together in a closed glass flask which was providedwith a mixer and a nitrogen atmosphere. The flask was placed in a waterbath. 40 g of sodium hydroxide, diluted with 40 g of water, was addedand the cellulose was mercerised for 90 minutes at 20° C. 44 g ofmonochloracetic acid, diluted with 11 g of water, and 1 g of alkylketenedimer dispersion having an AKD content of 10% by weight were added, andthe temperature was raised in 45 minutes to 70° C. The cellulose wasetherified for 90 minutes at 70° C. CMC was neutralised withhydrochloric acid. The byproducts of the reaction, sodium chloride andsodium glycolate, were washed out with 75% methanol, and the product wasdried at 80° C. to a moisture content of less than 8%. The AKD contentof the end product was 0.08%, the average molecular weight 270 000, andthe DS of the carboxymethyl group 0.59.

Examples 17-19

Samples 17-19 were prepared according to the procedure described inexample 16. In example 19 AKD was added during mercerisation.

TABLE 3 Molecular Degree of AKD content weight of substitution in CMC, %Example Raw material CMC of CMC by weight 17 wood pulp 60 000 0.77 0.07(Metsä-Botnia) 18 wood pulp 240 000 0.89 0.07 (Borregaard) 19 cottonlinter 380 000 0.80 0.7 (Buckeye, Temming)

Example 20

A granular detergent composition in accordance with the invention hasthe following basic formula:

TABLE 4 Component Wt. % C₁₂ Linear alkyl benzene sulfonate 9.31 C₁₄₋₁₅alkyl ether (0.35 EO) sulfate 12.74 Zeolite Builder 27.79 SodiumCarbonate 27.31 PEG 4000 1.60 Dispersant 2.26 C₁₂₋₁₃ Alcohol Ethoxylate(9 EO) 1.5 Sodium Perborate 1.03 Soil Release Polymer 0.41 Enzymes 0.59Hydrophobically modified cellulose ether 3.0 Perfume, Brightener, SudsSuppressor, Balance Other Minors, Moisture, Sulfate 100%

What is claimed is:
 1. A hydrophobically modified cellulose ether,wherein the hydrophobic modification has been carried out by using analkyl or alkenylketene dimer the formula of which is

wherein R is an alkyl or alkenyl group.
 2. A modified cellulose etheraccording to claim 1, wherein the alkyl or alkenyl chain has 5 to 22carbons.
 3. A modified cellulose ether according to claim 2, wherein thealkyl or alkenyl chain has 13 to 22 carbons.
 4. A modified celluloseether according to claim 1, wherein the alkyl or alkenyl chain has 14 to18 carbons.
 5. A modified cellulose ether according to claim 1, of theformula,

wherein R is an alkyl or alkenyl group.
 6. A modified cellulose etheraccording to claim 1, wherein the molecular weight of the celluloseether is 10 000-1,000
 000. 7. A modified cellulose ether according toclaim 6, wherein the molecular weight of the, cellulose ether is 20000-700
 000. 8. A modified cellulose ether according to claim 7, whereinthe molecular weight of the cellulose ether is 40 000-500
 000. 9. Amodified cellulose ether according to claim 5, wherein the modifiedcellulose ether consists of 0.001-10% by weight of the alkyl oralkenylketene dimer group.
 10. A modified cellulose ether according toclaim 9, wherein the modified cellulose ether consists of 0.01-2% byweight of the alkyl or alkenylketene dimer group.
 11. A modifiedcellulose ether according to claim 1, wherein the cellulose ether iscarboxymethyl cellulose.
 12. A modified cellulose ether according toclaim 11, wherein the carboxymethyl cellulose has a degree ofsubstitution of 0.2-2.
 13. A modified cellulose ether according to claim12, wherein the carboxymethyl cellulose has a degree of substitution of0.4-1.5.
 14. A modified cellulose ether according to claim 13, whereinthe carboxymethyl cellulose has a degree of substitution of 0.4-1.2. 15.A detergent composition comprising a hydrophobically modified celluloseether according to claim
 1. 16. A detergent composition according toclaim 15, mixed with water or an aqueous composition.
 17. A detergentcomposition according to claim 15, wherein the hydrophobically modifiedcellulose ether is hydrophobically modified carboxymethyl cellulose. 18.A detergent composition according to claim 17, wherein thehydrophobically modified carboxymethyl cellulose has a degree ofsubstitution of 0.4-0.6
 19. A hydrophobically modified cellulose ether,obtained by reacting an alkyl or alkenylketene dimer of the formula

with a cellulose ether, wherein R is an alkyl or alkenyl group.
 20. Amodified cellulose ether of the formula,

wherein R is an alkyl or alkenyl group.
 21. A modified cellulose etheraccording to claim 1, wherein the cellulose ether is sodiumcarboxymethyl cellulose.
 22. A modified cellulose ether according toclaim 1, wherein the cellulose ether is hydroxyethyl cellulose.
 23. Amodified cellulose ether according to claim 1, wherein the celluloseether is hydroxypropyl cellulose.